Coolant loss/coolant temp

Guys, Please tell me if this makes any sense..My 95 sts with 85K miles, had an external water pump leak, small, but after getting angry about the shop quote, I replaced it myself, along with the thermostat. No more antifreeze smell, no more external leaks. However, I would still have to add coolant every 3 or 4 days ( about half gallon, maybe less ) . I had the local shop to check "purge line" for blockage anf flush the radiator. Well, still had to keep adding a little coolant and the temp would go to 215-220 alot....So out of curiosity, I ran the heater wide open for about 30 minutes. ) It was 90 degrees outside).. Now, everything seems to be normal. Temp stays around 200 and havent had to add coolant in a couple of weeks. Does this make sense and if so why??

It isn't uncommon to have to add coolant after the system has been drained and refilled, as it purges trapped air. But not nearly as much as you were adding (and FWIW, the heater core is full flow at all times, so running the heater has no effect on coolant flow or bleeding the system). The coolant was going somewhere. How high we're you filling the surge tank? Full is to the "FULL COLD" line, about half way, where the two tank halves meet. Any excess coolant will be purged through the overflow.

Re: Coolant loss/coolant temp

If you have to add coolant, you have a leak, either internal or external. Common external leak points are the surge tank purge line nipple and the radiator side tanks. Remember, the condenser is mounted in front of the radiator, so the front of the side tanks are not visible. My '97 had a hairline crack at the nipple that was so fine, it was undetectable until the system heated up and pressurized. Only then would it seep ever so slightly. If you can't find a leak you may have to borrow a pressure tester from AutoZone and pressurize the system cold so as to avoid evaporation of the leaking coolant before it is spotted. All this of coarse is assuming that you are not overheating. 215 is not hot, but if it starts going much higher (try some WOT), then a block test may be in order.